viral zoonotic disease
Monkeypox is a viral zoonotic disease whose pathogen monkeypox virus is a DNA (deoxyribonucleic acid) virus belonging to the genus Orthopoxvirus of the family Poxviridae, and the smallpox virus that has ravaged thousands of years in human history. are “close relatives”. Monkeypox virus was first discovered in 1958, when a “pox-like” infectious disease appeared in a group of monkeys used for research, hence its name. Since the World Health Organization announced the complete eradication of smallpox in humans in 1980, monkeypox virus has become the orthopox virus with the greatest impact on public health.
According to an update on the WHO website on the 19th, although the monkeypox virus was first identified in monkeys, rodents are most likely its natural host. In Africa, squirrels, Gambian rats, and different species of monkeys have been found to be infected with monkeypox virus.
According to reports, monkeypox virus is mainly prevalent in West and Central Africa. In 1970, the Congo (DRC) discovered the first human case of monkeypox infection. Since then, most cases reported globally have been distributed in African countries such as Congo (Kinshasa), Congo (Brazzaville), Central African Republic, Nigeria, and Cameroon. For example, Congo (DRC) reported more than 6,000 human cases of monkeypox infection in 2020 and more than 3,000 in 2021.
The first monkeypox outbreak outside the African continent occurred in the United States in 2003, with dozens of people infected, and the source of infection can be traced back to Gambian rats and dormouse shipped from Ghana to the United States. Since 2018, Israel, the United Kingdom, Singapore and other countries have found monkeypox virus infections among travelers from Nigeria.
Direct contact with blood, body fluids, skin or mucosal lesions of infected animals, etc., may lead to the transmission of monkeypox virus from animals to humans. Eating improperly cooked infected animals is also a risk factor for “animal-to-human transmission.” In general, human-to-human transmission of monkeypox virus is uncommon. The human-to-human transmission route includes close contact with the respiratory secretions, skin lesions or contaminated items of infected persons, and it usually takes longer face-to-face to transmit respiratory droplets. In addition, mother-to-child transmission of monkeypox virus may occur through the placenta or through close contact during labor.
WHO emphasizes that in order to reduce the risk of infection, contact with wild animals in monkeypox virus-endemic areas should be avoided, especially to avoid unprotected contact with the meat, blood or other parts of sick or dead animals, and consumption of meat must be thorough. cooked.
Smallpox vaccine effective against monkeypox
According to WHO, the symptoms of monkeypox virus infection are similar to those of smallpox, but the clinical severity is less severe. The incubation period is usually 6 to 13 days and may be as long as 21 days. Early symptoms include fever, headache, swollen lymph nodes, muscle aches, and severe fatigue, among which swollen lymph nodes help differentiate monkeypox from smallpox. A few days after the fever develops into a large rash on the face and other parts of the body, and may lead to secondary infection, bronchopneumonia, sepsis, etc.
Monkeypox is usually a self-limiting disease, with most patients recovering within a few weeks. Severe cases are common in children or immunocompromised, and are also related to the underlying health status of the infected person, the degree of exposure to the virus, and the severity of complications. The fatality rate of monkeypox outbreaks varies widely, ranging from 3% to 6% in recent years.
Studies have shown that the smallpox vaccine is 85% effective in preventing monkeypox. In 2019, a vaccine based on an attenuated vaccinia virus was approved to prevent monkeypox, but it has not yet been administered widely. On the treatment side, an anti-variola virus drug tecavivir, previously approved by the U.S. Food and Drug Administration, was approved in Europe in 2022 to treat monkeypox and has not yet been widely used.
Recent transmissions are “atypical”
The number of countries reporting monkeypox cases and infections outside Africa has been increasing in recent days, and many infected people have no travel history to monkeypox-endemic areas. The WHO said the emergence of monkeypox cases in multiple “non-endemic countries” without direct travel links to disease-endemic areas was an “atypical” situation and the source of infection was still being investigated.
Does this mean the monkeypox virus has become more contagious? Michael Ryan, executive director of the WHO Health Emergencies Program, told a news conference a few days ago that the epidemiology of monkeypox has changed over the past few years and its emergence has expanded. In West Africa and the Sahel, increased climatic pressures have forced humans and animals to adapt to survive, potentially bringing animal populations closer to humans, sometimes competing for the same food resources. It is necessary to truly understand the deep ecology and human behavior of the relevant areas in order to try to prevent the spread of this disease to humans from its natural source.
Anne Rimoyne, a professor of epidemiology at the University of California, Los Angeles, pointed out that the increase in monkeypox cases may be related to the elimination of smallpox. After 1980, people were no longer vaccinated against smallpox, and immunity to monkeypox declined. Research published in 2010 by Rimoine and her colleagues showed that the incidence of monkeypox in Congo (DRC) has increased more than 14-fold over the past 30 years, from less than 1 case per 10,000 people to about 14 cases per 10,000 people.
Another perplexing phenomenon is that many of the recent infections are gay, bisexual or other men who have sex with men. Michael Head, a senior researcher in global health at the University of Southampton in the United Kingdom, said that it has not been confirmed that monkeypox virus is a sexually transmitted virus similar to HIV. “Close contact during sexual activity or intimate activities, including prolonged skin-to-skin contact, may is a key factor in spreading.”